Power consumption is a key care-about for most battery powered devices as it determines the time between battery recharges or replacements. As wireless local area network (WLAN) gets integrated in mobile phones and also in devices for internet of things (IoT), low power consumption of WLAN is becoming a critical design requirement. WLAN system uses Orthogonal Frequency Division Multiplexed (OFDM) signals.
OFDM signals are used in many technologies including WLAN and Long Term Evolution (LTE) due to their spectral efficiency and robustness to multipath fading channels. One of the drawbacks of OFDM signals is that they have high peak-to-average power ratio (PAR). Due to high PAR, power amplifier (PA) in the transmitter would have to be operated with a large back-off leading to poor PA efficiency. Alternatively, in integrated CMOS transceivers, large PAR increases the saturation power (Psat) requirement of the PA and can significantly increase the power consumption. In handheld applications, the poor efficiency of PA drains the battery.
Existing method to reduce the PAR includes a coding scheme which requires large look up tables (LUT) to be stored in the transmitter and receiver for both encoding and decoding. However, such a coding scheme cannot be used if it is not prescribed in the WLAN or LTE standard. Other conventional methods to reduce the PAR include selective mapping, partial transmit sequences and random phasor. These methods have high complexity and also require additional side information to be sent to the receiver, and hence are standard non-compliant. Therefore, a low complexity method to reduce PAR can help reduce the transmit power consumption and increase battery life.